Chemotaxis for polymorphonuclear leucocytes induced by soluble antigen- antibody complexes.

Guinea-pig soluble immune complexes formed either by simply mixing antibody and antigen in excess or by redissolving a washed immune precipitate with antigen, after incubation with fresh serum, could induce a migration of polymorphonuclear leucocytes in vitro. This chemotactic effect of soluble complexes, although less than that of insoluble complexes, persisted despite experimental changes in the specificity, the dose and the class of antibodies. Soluble complexes of various molecular compositions induced chemotaxis but the most efficient complex was of Ab 1 Ag 1 formula. Unlike larger complexes, the Ab 1 Ag 1 complexes induced little or no complement fixation. Another source of chemotactic mediators was needed, apparently related to the esterases of the contact system of coagulation.